Is chemotherapy safe in people with diabetes?

Cancer treatment can affect appetite, activity, hydration and blood glucose. Steroid medicines used with some chemotherapy can raise glucose, while nausea or reduced eating can make glucose fall when diabetes medicines continue unchanged. Diabetes may also affect kidney function, which can influence medicine choices and doses. Your oncology and diabetes teams may coordinate checks before treatment and during each cycle.

The plan may include reviewing insulin or tablet medicines, checking kidney function, choosing suitable food and drink during treatment, and making a plan for days when you cannot eat normally. Diabetes does not by itself decide whether chemotherapy is appropriate; the cancer, treatment goals, general health and current glucose pattern all matter.

Give the cancer team a complete list of diabetes medicines, glucose readings, devices and previous episodes of very high or low glucose. Ask which readings should prompt a call and whether you should change medicines on treatment days. Keep supplies for monitoring available, follow the agreed hydration and eating plan, and tell the team promptly if vomiting or diarrhoea prevents you from keeping fluids down.

Contact your treatment team urgently for repeated very high or low readings, confusion, unusual drowsiness, difficulty breathing, persistent vomiting, inability to drink, fever or signs of infection. Seek emergency help for severe breathing difficulty, collapse, or a person who cannot be awakened. Use the personalised thresholds supplied by your clinicians because they depend on your medicines and health.

Ask which chemotherapy medicines and supportive steroids may change glucose, how often to test, who adjusts diabetes treatment, and what to do if you eat less than usual. Confirm how kidney tests will be used, which symptoms require same-day advice, and whether your diabetes clinician should join treatment planning.